A SURVEY OF MINCED LAMB PACKAGED IN MODIF IED ATMOSPHERES

A survey of microbiological and physico-chemical parameters of minced lamb packed under modified atmosphere and sold by five major supermark ets nation-wide in the U.K. was made. Samples were analysed on the pur chase and on the expiry day. Lactic acid bacteria (Carnobacterium pisc icola, Carnobacterium divergens, Leuconostoc mesenteroides subsp. mese nteroides, Lactococcus raffinolactis), Brochothrix thermosphacta, pseu domonads (Pseudomonas fragi, Pseudomonas fluorescens, Pseudomonas lund ensis), Enterobacteriaceae and yeats, given in order of numerical impo rtance, were members of the microbial associations on the expiry day. Of the physico-chemical attributes pH decreased, glucose, glucose 6-ph osphate, gluconate were catabolised, and, L-, D-lactic and acetic acid and ammonia were produced. Dominance of lactic acid bacteria was refl ected in a decrease in pH, production of D-lactic and acetic acid and, following depletion of the carbohydrates, an oxidation of lactate iso mers to acetate. When B. thermosphacta was dominant these changes were not detected to the same extent. When a large population of pseudomon ads was present oxidation of glucose to gluconate occurred.